The money announced on Sunday will fund stage one of upgrading the Wyangala Dam, in the state's Central West, and delivering the new Dungowan Dam, near Tamworth, as well as investigations into a third dam on the Mole River, in the Northern Tablelands region.

The dams are part of the state government's $1 billion water infrastructure package announced in 2019 and co-funded with the federal government.

The 50/50 investment was to deliver a $650 million upgrade of Wyangala Dam and $480 million for the Dungowan Dam, Prime Minister Scott Morrison said in October.

At the time, NSW Premier Gladys Berejiklan described these announcements as historic given the last time a dam was built in NSW was in 1987.

She estimated the new dam will take about four years to build.

The dams are part of infrastructure that will aid regional and rural communities to build drought resistance into the future.

The joint venture will also help NSW free up funding for critical town water projects across the state.

An initial $24 million 50/50 investment for the proposed 100,000-megalitre Border Rivers project on the Mole River, near the Queensland border, was also announced.

All three projects have been declared Critical State Significant Infrastructure, with the $245 million to contribute towards final business cases, preconstruction and preliminary works for the Wyangala Dam wall raising and the Dungowan Dam.

Deputy Premier John Barilaro says the projects have the potential to provide economic and social benefits to hundreds of residents and businesses, create hundreds of regional jobs, and secure water for their communities.

"The time is now to build dams in NSW, to be bold in our vision for regional communities and take control of our future," Mr Barilaro said in a statement on Sunday.

"We are disadvantaging future generations if we don't learn our lesson in this drought and build more dams now.

"Today sets a new precedent for building dams in NSW and will act as the blueprint for growing the prosperity in our regions by investing in our state's water security."

Minister for Water Melinda Pavey said the works are needed to make sure more water can be stored in between periods of drought to sustain local communities.

"These once-in-a-generation infrastructure projects will improve water security for farming, irrigation, industry and homes, and boost local economies," Ms Pavey said in a statement.

"Raising Wyangala Dam's wall will increase its storage capacity by 53 per cent, or an additional 650 gigalitres, increasing drought resilience for the entire Lachlan Valley."

Australian Associated Press